Hydrogen sulfide (H2S) is a newly recognized signaling molecule with very potent cytoprotective actions. The fields of H2S physiology and pharmacology have been rapidly growing in recent years, but a number of fundamental issues must be addressed to advance our understanding of the biology and clinical potential of H2S in the future. It is important to study the chemistry and pharmacology of exogenous H2S, to be aware of the limitations associated with the choice of chemical agents used to generate H2S in vitro and in vivo. In this regard, synthetic H2S-releasing agents (i.e. H2S donors) are important research tools and potentially very valuable therapeutic candidates for drug development. However, currently available H2S donors are very limited in terms of research use or clinical development since those compounds are very short-lived and the timing and amount of H2S release is largely uncontrollable. To solve these problems, we have recently developed four types of new H2S donors based on N-mercapto, perthiol, gem-dithiol, and phosphorodithioate templates. H2S generations from these donors can be controlled by different mechanisms and the rates of H2S generation can be regulated upon structural modifications. We also found that the administration of H2S donors at the time of reperfusion significantly decreased infarct size and preserved left ventricular function in an in vivo murine model of myocardial ischemia/reperfusion injury. In this project, we plan to develop a toolbox of long-lasting and controllable H2S releasing agents and apply them to explore the pharmacology of H2S under pathological disease states in in vitro and in vivo model systems. Three Specific Aims will be pursued: 1) to design, synthesize, and evaluate controllable H2S donors, 2) to screen the activities of synthetic H2S donors under in vitro conditions; and 3) to examine the cardioprotective actions of donors in acute myocardial ischemia/reperfusion (MI/R) injury and chronic heart failure. We believe that the proposed research will expand our understanding of the chemistry/pharmacology of H2S and provide valuable tools and information to facilitate H2S biomedical research.